Hissing sound - Help?

[fsp]

Ok, I have looked through the archives but have not been able to find any related posts. I have noticed a hissing sound, (sounds like a vacuum leak or a turbo wastegate, btw - the car is stock, there is no turbo), when I run the engine to near red line. I have an 01', 6 speed, and when I get on it and shift through the gears, there is a noticeable hiss comming from the engine bay. Under normal driving conditions, the sound is not there, but tach it up and go, and the sound appears very clearly. Can any one help with this? Is this normal? :confused

 

[PIPO]

Hi
I had the same sound but particulary noticeble around 1800/2000 RPM. After I can't say because of the B&B PRT exhaust sound. It is the intake manifold!
It seems to be a very fragil part because when they first changed it on my car it was brocken during shipping, the second was brocken during installation and I'm waiting for the third. meantime I'm petestrian.

 

[Talmadge]

I sure would like info about this hissing problem. My problem sounds more like a whistle that occures during hard acceleration. 02 Vert.

 

[PIPO]

Ok, I have looked through the archives but have not been able to find any related posts. I have noticed a hissing sound, (sounds like a vacuum leak or a turbo wastegate, btw - the car is stock, there is no turbo), when I run the engine to near red line. I have an 01', 6 speed, and when I get on it and shift through the gears, there is a noticeable hiss comming from the engine bay. Under normal driving conditions, the sound is not there, but tach it up and go, and the sound appears very clearly. Can any one help with this? Is this normal? :confused

Hi undoubtly it is the intake manifold. Before GM changed it on my car the sound was noticeble: like a turbo. As I said it in my former post because of the sound of my exhaust I certainely couldn't hear it, but it may certainely be there.
This problem is known by GM and you will find the service bulletin the Knowledgebase.

 

[ronman99vette]

Did either of you get the hissing sound resolved. I have a noticeable hissing sound under acceleration also. It does not happen all the time though. I'm afraid the mechanic will have a problem duplicating the sound and was wondering what you found out.
Thanks

 

[Talmadge]

At this time I know nothing about the problem, will talk with the Chevy Dealer next week. I did notice the problem to appear more so after the engine was hot (220 degree). Sure hope we can get this taken care of.